Electrical connectors for distribution plate and rack and panel applications

ABSTRACT

One family of connectors, having miniature size and close contact spacing, provides both an Input/Output (I/O) connector (i.e., a pluggable connector for connecting a plurality of leads to an automatically wire-wrappable electrical distribution plate or computer back panel) and a Rack-and-Panel (R/P) connector (i.e., a pluggable connector for connecting one plurality of leads to another plurality thereof, such as required for connecting an electrical equipment chassis to its mounting rack). The family comprises a R/P receptacle, an I/O receptacle, and a plug which can mate with either receptacle. The plug and both receptacles include flat, fork-like androgynous contacts, those in the plug being recessed in individual cavities and those in the receptacles having free-standing mating (nose) portions. The connectors have orientation keying in the form of side grooves in the plug arranged in an asymmetric pattern; these mate with complimentary integral ribs on (1) the inside of an upstanding upper wall of the R/P receptacle insulator, or (2) the insides of opposed upstanding short side walls of the I/O receptacle insulator. Connector keying is provided by an androgynous pin mounted at each side of the plug, the R/P, and the I/O receptacle ; each pin is asymmetric and is mountable in any of six different positions. The I/O receptacle comprises an assembly of flat modules (center, side, and keying) having cylindrical bottom bushings for holding each module to a foraminous metal plate and holding the module&#39;&#39;s contacts. The center module contains, in addition to the aforementioned short side walls, bushings for holding a plurality of contacts and an opening to accommodate a socket for a connecting screw. The side modules, provided in pairs, hold sufficient additional contacts to mate with whatever size plug is used. The keying modules, also provided in pairs, hold the connector keying pins.

United States Patent Ruehlemann et al.

[ 1 July 4,1972

154] ELECTRICAL CONNECTORS FOR DISTRIBUTION PLATE AND RACK AND PANEL APPLICATIONS [72] Inventors: Herbert E. Ruehlemann, Huntingdon Valley; Alexander Wontorsky, Philadelphia,

[21] Appl. No.: 112,164

[52] U.S.Cl. ..339/l26 RS,339/186 M, 339/221 M [51] Int. Cl. ..l-I02h l/02, HOlr 13/64 [58] FieldofSearcli ..339/l7 R, 17 M, 18R, 18 B,

339/184 R, 184 M, 186 R, 186 M, 191 M, 192-196, 221, 125, 126, 128', 317/101 C, 101 CB, 101 CC,

[56] References Cited UNITED STATES PATENTS 3,621,444 11/1971 Stein ..339/221 M 3,518,610 6/1970 Goodman et al..... ....339/176 MP 3,166,372 1/1965 .Iust ...339/221 M 3,086,074 4/1963 Just et a1. ..339/l86 M FOREIGN PATENTS OR APPLICATIONS 235,622 1/1960 Australia ..339/l84 M 793,871 4/1958 Great Britain. ...339/221 M 1,466,941 12/1966 France ..339/184 M Primary Examiner-Marvin A. Champion Assistant Examiner-Lawrence l. Staab Attorney-D. R. Pressman 5 7 ABSTRACT One family of connectors, having miniature size and close contact spacing, provides both an Input/Output l/O) connector (i.e., a pluggable connector for connecting a plurality of leads to an automatically wire-wrappable electrical distribution plate or computer back panel) and a Rack-and-Panel (RIP) connector (i.e., a pluggable connector for connecting one plurality of leads to another plurality thereof, such as required for connecting an electrical equipment chassis to its mounting rack). The family comprises a R/P receptacle, an l/O receptacle, and a plug which can mate with either receptacle. The plug and both receptacles include flat, fork-like androgynous contacts, those in the plug being recessed in individual cavities and those in the receptacles having freestanding mating (nose) portions. The connectors have orientation keying in the form of side grooves in the plug arranged in an asymmetric pattern; these mate with complimentary integral ribs on (1 the inside of an upstanding upper wall of the RIP receptacle insulator, or (2) the insides of opposed upstanding short side walls of the l/O receptacle insulator. Con nector keying is provided by an androgynous pin mounted at each side of the plug, the RIP, and the [/0 receptacle each pin is asymmetric and is mountable in any of six different positions. The 1/0 receptacle comprises an assembly of flat modules (center, side, and keying) having cylindrical bottom bushings for holding each module to a foraminous metal plate and holding the modules contacts. The center module contains, in addition to the aforementioned short side walls, bushings for holding a plurality of contacts and an opening to accommodate a socket for a connecting screw. The side modules, provided in pairs, hold sufficient additional contacts to mate with whatever size plug is used. The keying modules, also provided in pairs, hold the connector keying pins.

13 Claims, 22 Drawing Figures Patented July 4, 1972 3,675,185

6 Sheets-Sheet 1 28 FIG. 2-1/0 RECEPTACLE INVENTORS HERBERT E. RUEHLENANN ALEXANDER WONTORSKY WWW) ATTORNEY Patented July 4, 1972 3,675,185

6 Shuts-Sheet 2 FIG.4

R/P RECEPTACLE END FIG.5 R/P RECEPTACLE SIDE INVENTOQ HERBERT E. RUEHLE NN ALEXANDER WONTORSKY WWW ATTORNEY Patented July 4, 1972 6 Sheets-Sheet 5 OOOOOOO OOOOOOO OOOOOOO FIG PLUG-END Q++++++ ++++++nl ++++++fll I6. 8 PLUG BOTTOM INVENTORS HERBERT E. RUEHLEMANN ALEXANDER WONTORSKY WWW ATTORNEY I E m I 8 F|G.17 5|D MODUL Patented Jul 4, 1972 3,675,185

6 Sheets-Sheet 4 FIG.1O

I/O RECEPTACLE TOP FlG.11-I/O RECEPTACLE X SECTION FIG 16-S|DE MODULE INSULATOR r'kywyyyy TOP a y 6 6 6 6 a 34 E|G.18-SIDE MODULE 6 6 5 6 6 INSULATOR -TOP INVENTO HERBERT E. R 1.5mm ALEXANDER NTORSKY WWW) ATTORNEY INSULATOR-SIDE Patented July 4, 1972 6 Shuts-Sheet 5 as CENTER MODULE 42 FIG 2- CENTER MODULE |NSULATOR-TOP |NSULATOR- FIG. 14 CENTER MODULE INSULATOR INVENTORS HERBERT E. RUEHLEMANN ALEXANDER WONTDRSKY Fl. 22-I b CONTACT MOUNTING ATTORNEY Patented July 4, 1972 3,675,185

6 Sheets-Sheet 6 92 9e 94 88 HQ 1 C q I: 1

EIQZO I/O CONTACT 92 6 8B 92 36 86 fiL/L CL )L l as, 21 1/0 CONTACT FIG. 19 in; 1/0 CONTACT94 INVENTORS HERBERT UE HLE MANN ALEXAND WONTORSKY WM) S|DE-MODULE INSULATOR ATTORNEY PIC-3.15

ELECTRICAL CONNECTORS FOR DISTRIBUTION PLATE AND RACK AND PANEL APPLICATIONS CROSS REFERENCES TO RELATED APPLICATIONS D.

The invention of the present application preferably embodies the inventions shown in US Pat. No. 3,248,686, granted Apr. 26, 1966 to H. E. Ruehlemann, entitled "Contact with Locking Feature", and US. Pat. No. D. 173,694, granted Dec. 21, 1954 to B. Fox, entitled Electrical Connector".

BACKGROUND OF INVENTION I. Field of Invention The present invention relates to a family of miniature connectors which can serve as Rack-and-Panel (RIP) connectors and Input/Output (IIO) connectors. An RIP connector may be defined, for the present context, as one which is designed mainly for providing a plurality of simultaneous connections to an electrical equipment chassis (panel) and its mounting rack, but which can be used in any application wherein one plurality of wires is to be connected simultaneously to another plurality of wires, where neither plurality of wires is to be machine-wrapped to the tails of the contacts in the connector. An l/O connector is one which can provide a plurality of simultaneous connections to a computer back panel or other electrical distribution plate which carries wires which are to be machine wrapped to the tails of the contacts of a platemounted receptacle of the connector.

2. Description of the Prior Art Because of the requirement for very rigid, precisely positioned wire-wrappable contact tails in an I/O connector, (which cannot easily be filled by a R/P connector because the contacts thereof must be insertable and removable) and the requirement for a portable connector body in a RIP connector (which cannot easily be filled by an I/O connector because an IIO connector must be flat and plate-mountable), RIP and I/O connectors generally are designed, cataloged, and used separately. Thus it was not possible to mate a plug or receptacle of an I/O connector with the receptacle or plug of an RIP connector. This is disadvantageous because applications are often found in the electronic industry when one group of wires, terminated for example in an RIP plug, must be connected to an electrical distribution plate as well as an equipment chassis. Adapters, therefore, were required to facilitate this type of interconnection. In addition, connector manufacturers who produced and sold both RIP and I/O connectors had to expend relatively large sums to tool two separate plugs and two separate receptacles. This tooling cost was compounded greatly when connectors of several sizes had to be fabricated.

With respect to I/O connectors, the need for miniaturization created additional problems. An IIO plate-mounted receptacle must contain many contacts having nose or mating sections extending above the plate and wire-wrappable tail sections extending below the plate. The contacts must be very rigidly mounted (to withstand the pressures encountered during wire wrapping), must have very accurate positioning, and of course must be insulated from each other and from the plate. These problems, although not serious when spacing between adjacent contacts is on the order of 200 mils, become redoubtable when contacts are mounted with spacings of 100 mils. A separate insulator was used to mount each contact in a respective hole in the plate where contact spacing of 200 mils was employed. However it was found impossible to use such an arrangement where contact spacing of 100 mils was employed since the insulators became too small and thin to hold the contacts rigidly, provide adequate positioning accuracy, and resistance to physical breakdown.

Accordingly, several objects of the present invention are: l to provide a connector family for I/O and RIP applications in which two separate plugs and two separate receptacles need not be provided and (2) to provide an I/O plate-mounted receptacle in which wire-wrappable contacts can be mounted on a grid spacing of I00 mils. Other objects are to provide novel modular arrangement for an I/O plate-mounted recepta cle, to provide novelorientation keying for an I/O plate receptacle, and to provide a novel connector keying arrangement for a connector family used in [IQ and RIP applications. Further objects and advantages of the present invention will become apparent from a consideration of the ensuing desc ription thereof.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an axonometric view of a plug according to the present invention.

FIG. 2 is an axonometric view of an I/O receptacle according to the invention mounted on a plate.

FIGS. 3, 4, and 5 are top, end, and side views of an RIP receptacle according to the invention (FIGS. 4 and 5 also show a chassis).

FIGS. 6, '7, 8, and 9 are top, side, bottom, and end views of the plug.

FIG. 10 is a top view of the I/O receptacle, and

FIG. I l is a cros-sectional side view along the lines I1 I I of FIG. 10.

FIGS. l2, l3, and I4 are top, side, and axonometric views of the center module of the insulator of the [[0 receptacle of FIG. 2.

FIGS. l5, l6, l7 and 18 are axonometric, top, side, and end views of the side module of the insulator of the IIO receptacle.

FIGS. 19, 20, and 21 are axonometric, face, and edge views of a contact used in the U0 receptacle.

FIG. 22 is a view of a contact (full section) mounted in an I/O insulator on a plate (partial cross-section DESCRIPTION OF THE PREFERRED EMBODIMENT According to the present invention, a family of miniature RIP and IIO connectors comprises an RIP receptacle, an I/O receptacle, and a plug which is common to and can mate with either receptacle.

FIG. 1 shows a view of the common plug. This plug comprises an insulator 10, a plurality of contacts (not visible) which are mounted in individual cavities such as 12 which extend through insulator 10, a connecting screw assembly 14, and two connector keying pins, one of which is shown at 16. The contacts preferably are androgynous and of the selflocking type shown in the aforementioned Ruehlemann patent. These contacts have a tail section of the type which can be crimped around the insulation and conductor of a wire so that, after assembly and wiring, a plurality of wires, such as shown at 18, will lead into the respective holes 12 at the top of the plug.

FIG. 2 shows the IIO receptacle 20 according to the invention mounted on a forarninous (apertures not indicated) plate 22. Receptacle 20, as shown in FIG. 2, comprises five separate modules: a center module 24, identical side modules 26, and identical keying modules 28. Each module comprises an insulator which is mounted on metal plate 22 by means of a force fit between bushings (not shown in FIG. 2) and the apertures in plate 22. An androgynous polarizing pin 32 is mounted in the insulator 30 of each keying module 28. Each side module 26 comprises a flat insulator in which are mounted a plurality of contacts such as 36. The center module 24 comprises an insulator 38 in which are mounted a plurality of contacts (not shown) similar to 36. Insulator 38 contains upstanding walls 40 and 42 which have inwardly facing orientation keying ribs 44, 46, and 48. Insulator 38 contains an aperture 50 in the center thereof to accommodate threaded socket 52 which is staked or otherwise mounted to an aperture in plate 22. Socket 52 receives the threaded end (see FIG. 7) of connecting screw assembly 14 of the plug of FIG. 1.

The R/P receptacle 54 of FIGS. 3, 4, and 5 comprises an insulator 56, a plurality of contacts such as shown in 58, keying pins I6 identical to those of FIG. I, and a threaded socket 60 for receiving the threaded end of the connecting screw assembly 14 of FIG. 1. Mounting hardware 62 is provided for bolting receptacle 54 to a chassis (FIGS. 4 and 5). In practice, a wire such as shown in 18 is connected to each contact 58 by crimping the tail portions (not shown) of contact 58 around such wire as indicated in the aforementioned Ruehlemann patent and as practiced in the plug of FIG. 1.

Insulator 56 of R/P receptacle 54 comprises an upper collar 55 having integral orientation keying ribs 44, 46, and 48 similar to those of the I/O receptacle.

When the plug of FIG. I is used with the I/O receptacle FIG. 2, an I/O connector is provided by which a plurality of leads or wires can be removably attached to an electrical distribution plate of the type having connectors with wire-wrappable terminals thereon. The tails of the contacts 36 of receptacle 20 (FIG. 2) are designed for machine wire wrapping so that these contacts can be wired automatically to the contact tails of other receptacles or terminals on plate 22 automatically. When the plug of FIG. I is used with an R/P receptacle of FIGS. 3 to 5, an RIP connector is provided by which a plurality of wires can be removably connected to another plurality of wires, where neither plurality is to be machine wire-wrapped. It is thus seen that a single plug can serve as the mating half of either an I/O receptacle or an RIP receptacle.

To accommodate largely differing numbers of contacts economically, several sizes of plugs and receptacles are required for the RIP connector. However since the I/O receptacle is in modular form, its size can readily be changed to accommodate the differing sized plugs by adding or subtracting side modules from the basic arrangement shown in FIG. 2. For example, the arrangement shown in FIG. 2, which includes center module 24, two side modules 26, and the two polarizing modules 28, holds 75 contacts: 33 contacts in the center module and 2! contacts in each of the side modules. If a smaller connector with 33 or less contacts is required, the side modules 26 would not be used and the polarizing modules 28 would be mounted adjacent center module 24; a smaller plug would be provided. Conversely a connector requiring more than 75 contacts would use four or more side modules with an appropriately larger plug.

The plug, shown in detail in FIGS. 6 to 9 as well as FIG. 1, is shaped so that the insulator 10 thereof comprises a wide center portion 66, a distinctly narrower integral top portion 68, and another distinctly narrower bottom portion 70. The plug (as well as the RIP receptacle) can be used with a cable clamp and cover (not shown) which fits around the sides of top portion 68 and thereby is flush with the sides of center portion 66. Bottom portion 70 is designed to fit into upstanding collar 55 of the RIP receptacle or between the side walls 40 and 42 of the I/O receptacle. The connecting screw assembly 14, of conventional design, is rotatably mounted within insulator 10 so that when the plug is mated with either type receptacle, screw 14 can be tightened manually in order to draw the mating halves of the connector together.

The bottom portion 70 of insulator 10 has a keying groove 72 on one side thereof and two keying grooves 74 and 76 on the opposite side thereof. Since these grooves are asymmetric with respect to a center horizontal line drawn through the view of FIG. 8, and since both the I/O and R]? receptacles have corresponding ribs 44, 46, and 48 for mating with these grooves, the plug can be mated with either receptacle in but one mutual orientation.

In order to insure that a plug is mated with the proper one of several possible receptacles, connector keying is provided by means of the pins 16, each of which comprises a six-sided (hexagonal) rod which has a threaded end so that it can be bolted to the plug by a nut 78. Along most of the length of the pin, a longitudinal half-section has been removed (as shown in FIGS. 7 and 9) so that part of the pin comprises an asymmetric foursided member. The six-sided portion of the pin is mounted in a hexagonal cavity of the insulator so that the pin can be mounted in any of six possible orientations. Since both the R/P and I/O receptacles also have pins which can be mounted in any of six possible orientations, the orientation of the pins in the plug and a receptacle must match in order for two to be mated. By utilizing the two pins of each receptacle in this manner, each of 36 plugs can be mated only with a unique one of 36 possible receptacles.

Further details of the U0 receptacle shown in FIG. 2 are presented in FIGS. 10 and 11. The receptacle can be assembled or installed in either of two ways l the individual contacts 36 can be inserted in the center and side modules, which thereafter are assembled to plate 32, or (2) the center and side modules can be assembled to plate 22 and the contacts 36 can thereafter be inserted into the openings in the mounted modules. In either case, the contacts can be inserted manually or by automatic machinery, as will be appreciated by those skilled in the art.

The keying modules 28 also can be assembled in either of two ways, i.e., the modules can be installed to the plate and thereafter the keying pins 32 can be mounted or the keying pins 32 can be mounted in the insulator 30, whereafter the entire module 28 is installed to the plate. The insulator 30 of keying module 28 has upper and lower collars and 82, respectively, to hold the keying pins 32. As with the plug and RIP receptacle, the opening in this collar is hexagonal so that the pin can be mounted in any of six possible positions. The bottom collar 82 fits lightly into an aperture in the plate. The insulator 30 preferably also includes six solid bottom hubs or bushings (not shown) which fit into respective apertures in the plate by force fit. Three of these bushings preferably are mounted on either side of collar 82.

Threaded socket S2 is installed on plate 22 in a separate operation, preferably before installation of center module 24, by staking or clinching.

Details of the insulator of side module 26 are shown in FIGS. l6, l7, and 18. As shown, the insulator comprises essentially a flat body of insulating material (preferably a thermoplastic material such as nylon) having bushings such as 84 protruding from the lower surface thereof. Each of these bushings has an opening therethrough which extends to the upper surface of insulator 34 as shown at 86. The upper portion of each opening or through hole 86 is widened to accommodate the widened nose portion of a contact. Each of the bushings has a tapered lead-in portion and a body portion with straight sides which engages the respective apertures in plate 22 by force fit.

Details of the insulator of center module 24 of the U0 receptacle are shown in FIGS. 12 to 14. The insulator includes bottom bushings 84 identical to those of the side module insulator 34.

Details of an l/O receptacle contact 36 are shown in FIGS. 19 to 21. Each contact includes a nose or mating portion 88, a body portion 90, and a tail portion 92. The nose portion 88 is fork-like (bifurcated) as shown in the aforementioned Fox design patent. This type of contact is sold under the trademark VARICON. Body portion 90 includes a pair of ears 94 to aid in engagement of the bushings of the side and center modules 34 and 38 and a pair of shoulder portions 96 to inhibit withdrawal of the contacts after they are inserted into the respective openings in the insulator. The tail portion 92 has a square cross-section to enable wire-wrapped connections to be made thereto.

Details of the manner in which the contacts are mounted in their respective openings in the I/O insulator are indicated in FIG. 22. It will be noted that the contacts shoulder portions 96 are below the plate 22 so as to inhibit withdrawal of the contact after insertion.

The plug and R/P insulators may be formed of any commonly used thermoplastic or thermosetting material such as polycarbonate, nylon, or diallyl phthalate (DAP). However, a thermosetting material such as DA? is preferred. Because of the need for flexibility and to be able to insert the contacts and restrain them in the plate by force fit, the I/O insulator should be of a rigid, yet slightly deformable thermoplastic material, such as nylon. The contacts preferably are formed of phosphor bronze with gold plating.

By using a several piece modular insulator arrangement for an l/O receptacle, wherein each module holds a plurality of contacts, it has been found possible to mount contacts with wire-wrappable tails on centers of as little as 100 mils, while still being able to insure a high degree of accuracy of contact placement, excellent contact rigidity, and excellent insulator electrical and mechanical strength.

When the plug is used in conjunction with the RIP receptacle to provide an RIP connector, either the receptacle, the plug, or both can be chassis or rack mounted, or either or both can be attached to a "free" cable. When attached to a cable, a suitable cover and cable clamp preferably should be attached to either the top of the plug or the bottom of the RIP receptacle by means of suitable bolts.

While the above description contains many specificities, these should not be construed as limitations upon the scope of the invention but merely as an exemplification of one preferred embodiment thereof. The true scope of the invention is indicated by the subject matter of the appended claims and the legal equivalents thereof.

We claim:

I. An input/output receptacle comprising a first insulator having opposed upper and lower major surfaces interconnected by an edge surface, the area of each of said major surfaces being greater than the entire area of said edge surface so that said first insulator consists of a substantially flat body except for (a) a plurality of integral cylindrical bushings protruding downwardly from said lower surface and (b) integral orientation keying means protruding upwardly from said upper surface for insuring that said receptacle can be connected to a mating plug in but one mutual orientation, an opening through each of such bushings extending to said upper surface such that said insulator has a corresponding plurality of through holes therein, each of said bushings having a tapered end portion remote from said lower surface and a non-tapered body portion adjacent said lower surface, thereby to permit said bushing to be inserted by force fit into respective apertures in a perforated plate, each of said holes having a contact mounted therein, each contact comprising a mating portion, a tail portion, and a body portion interconnecting said mating and tail portions, the body portion of each contact being mounted in a respective one of said through holes, the mating portion of each contact extending upwardly from said upper surface, and the tail portion of each contact extending downwardly from the end portion of each bushing.

2. The receptacle of claim 1 wherein substantially each of said contacts is mounted a distance not greater than 100 mils from its adjacent contacts.

3. The receptacles of claim 1 wherein said integral orientation keying means comprises a pair of integral walls projecting orthogonally upward from opposite sides of said upper surface of said insulator, each of said walls having at least one integral rib projecting from the surface of said wall which faces said other wall.

4. The receptacle of claim 3 further comprising a plug containing a plurality of contacts designed to mate, respectively, with said contacts of said receptacle, said plug comprising an insulator in which said contacts are mounted, said insulator having side walls containing a plurality of grooves designed to engage said integral ribs of said receptacle so as to permit mating of said plug and receptacle in but one mutual orientation.

5. The receptacle of claim 4 further including a rack-andpanel receptacle comprising an insulator having a plurality of contacts mounted therein which are designed to mate with said plurality of contacts in said plug and which each consist of a mating portion connected to a tail portion by a body portion, said rack-and-panel insulator being thick enough to contain the body and tail sections of said contacts and having means for mounting said rack-and-panel receptacle substantially on one side of a mounting plate, said rack-and-panel receptacle insulator having upstanding walls surrounding said mating portions of said contacts, thereby to form a cavity for receiving said plug, the inner surfaces of said upstanding walls having a plurality of integral keying ribs designed to mate with said grooves of said plug such that said plug and said rack-andpanel receptacle can mate in but one mutual orientation.

6. The receptacle of claim I further including a perforated plate, the apertures of which are narrower than said body portions of said bushings, said receptacle being mounted on said plate with said bushings being mounted in said respective apertures in said plate by interference fit.

7. The receptacle of claim 6 wherein said insulator is formed of a thermoplastic insulating material, each through hole in said insulator having a portion adjacent said upper surface which has a greater cross-sectional area than any other portion thereof, the body portion of each contact having two portions with relatively wide and narrow cross-sectional areas,

respectively, corresponding to the two different-sized areas of each through hole so that each of said contacts will seat firmly in a respective one of said through holes.

8. The receptacle of claim 7 wherein the body portion of each of said contacts has a pair of integral barbs with shoulders facing the mating portion of each contact, said barbs being positioned such that said shoulders underly a lower surface of said plate, thereby to inhibit withdrawal of said contact from said receptacle.

9. The receptacle of claim 6 further including a pair of side modules on said plate on opposite sides of said flat insulator, thereby to form a larger receptacle, each of said side modules comprising a second flat insulator having major upper and lower surfaces and a plurality of integral cylindrical bushings protruding therefrom similar to those of said first insulator, and having a plurality of contacts mounted in said holes, the bushings of said second insulators being held in said apertures of said plate by interference tit.

10. The receptacle of claim 9 further including a pair of keying modules mounted on said plate on opposite sides of said side modules, each of said keying modules comprising a body of insulating material having upper and lower surfaces with a plurality of integral bushings protruding from said lower surface thereof, said bushings of said keying modules being mounted in said apertures of said plate by interference fit, each of said keying modules having a keying member mounted therein.

ll. The receptacle of claim 10 wherein said integral orientation keying means comprises a pair of integral walls projecting orthogonally upward from opposite sides of said upper surface of said insulator, each of said walls having at least one integral rib projecting from the surface of said wall which faces said other wall, and further including a plug comprising a plurality of contacts designed to mate, respectively, with said contacts of said larger receptacle, said plug comprising an insulator having side walls containing a plurality of grooves designed to engage said integral ribs of said larger receptacle so as to permit mating of said plug and larger receptacle in but one mutual orientation, said plug also containing a plurality of keying members designed to mate, respectively, with said keying members of said keying modules of said receptacle.

12. The receptacle of claim 10 wherein said keying member comprises a metal pin, at least a part of which has an asymmetric cross-section and wherein said keying module includes means for mounting said pin in any one of a plurality descrete positions.

13. The receptacle of claim 12 wherein said means for mounting said pin comprises a boss, integral with said keying module and having a hollow core, the internal surface of which comprises a plurality of flat sides and said metal pin also has at least two flat sides which mate with two corresponding flat sides of said core.

* l i O i 

1. An input/output receptacle comprising a first insulator having opposed upper and lower major surfaces interconnected by an edge surface, the area of each of said major surfaces being greater than the entire area of said edge surface so that said first insulator consists of a substantially flat body except for (a) a plurality of integral cylindrical bushings protruding downwardly from said lower surface and (b) integral orientation keying means protruding upwardly from said upper surface for insuring that said receptacle can be connected to a mating plug in but one mutual orientation, an opening through each of such bushings extending to said upper surface such that said insulator has a corresponding plurality of through holes therein, each of said bushings having a tapered end portion remote from said lower surface and a non-tapered body portion adjacent said lower surface, thereby to permit said bushing to be inserted by force fit into respective apertures in a perforated plate, each of said holes having a contact mounted therein, each contact comprising a mating portion, a tail portion, and a body portion interconnecting said mating and tail portions, the body portion of each contact being mounted in a respective one of said through holes, the mating portion of each contact extending upwardly from said upper surface, and the tail portion of each contact extending downwardly from the end portion of each bushing.
 2. The receptacle of claim 1 wherein substantially each of said contacts is mounted a distance not greater than 100 mils from its adjacent contacts.
 3. The receptacles of claim 1 wherein said integral orientation keying means comprises a pair of integral walls projecting orthogonally upward from opposite sides of said upper surface of said insulator, each of said walls having at least one integral rib projecting from the surface of said wall which faces said other wall.
 4. The receptacle of claim 3 further comprising a plug containing a plurality of contacts designed to mate, respectively, with said contacts of said receptacle, said plug comprising an insulator in which said contacts are mounted, said insulator having side walls containing a plurality of grooves designed to engage said integral ribs of said receptacle so as to permit mating of said plug and receptacle in but one mutual orientation.
 5. The receptacle of claim 4 further including a rack-and-panel receptacle comprising an insulator having a plurality of contacts mounted therein which are designed to mate with said plurality of contacts in said plug and which each consist of a mating portion connected to a tail portion by a body portion, said rack-and-panel insulator being thick enough to contain the body and tail sections of said contacts and having means for mounting said rack-and-panel receptacle substantially on one side of a mounting plate, said rack-and-panel receptacle insulator having upstanding walls surrounding said mating portions of said contacts, thereby to form a cavity for receiving said plug, the inner surfaces of said upstanding walls having a plurality of integral keying ribs designed to mate with said grooves of said plug such that said plug and said rack-and-panel receptacle can mate in but one mutual orientation.
 6. The receptacle of claim 1 further including a perforated plate, the apertures of which are narrower than said body portions of said bushings, said receptacle being mounted on said plate with said bushings being mounted in said respective apertures in said plate by interference fit.
 7. The receptacle of claim 6 wherein said insulator is formed of a thermoplastic insulating materiAl, each through hole in said insulator having a portion adjacent said upper surface which has a greater cross-sectional area than any other portion thereof, the body portion of each contact having two portions with relatively wide and narrow cross-sectional areas, respectively, corresponding to the two different-sized areas of each through hole so that each of said contacts will seat firmly in a respective one of said through holes.
 8. The receptacle of claim 7 wherein the body portion of each of said contacts has a pair of integral barbs with shoulders facing the mating portion of each contact, said barbs being positioned such that said shoulders underly a lower surface of said plate, thereby to inhibit withdrawal of said contact from said receptacle.
 9. The receptacle of claim 6 further including a pair of side modules on said plate on opposite sides of said flat insulator, thereby to form a larger receptacle, each of said side modules comprising a second flat insulator having major upper and lower surfaces and a plurality of integral cylindrical bushings protruding therefrom similar to those of said first insulator, and having a plurality of contacts mounted in said holes, the bushings of said second insulators being held in said apertures of said plate by interference fit.
 10. The receptacle of claim 9 further including a pair of keying modules mounted on said plate on opposite sides of said side modules, each of said keying modules comprising a body of insulating material having upper and lower surfaces with a plurality of integral bushings protruding from said lower surface thereof, said bushings of said keying modules being mounted in said apertures of said plate by interference fit, each of said keying modules having a keying member mounted therein.
 11. The receptacle of claim 10 wherein said integral orientation keying means comprises a pair of integral walls projecting orthogonally upward from opposite sides of said upper surface of said insulator, each of said walls having at least one integral rib projecting from the surface of said wall which faces said other wall, and further including a plug comprising a plurality of contacts designed to mate, respectively, with said contacts of said larger receptacle, said plug comprising an insulator having side walls containing a plurality of grooves designed to engage said integral ribs of said larger receptacle so as to permit mating of said plug and larger receptacle in but one mutual orientation, said plug also containing a plurality of keying members designed to mate, respectively, with said keying members of said keying modules of said receptacle.
 12. The receptacle of claim 10 wherein said keying member comprises a metal pin, at least a part of which has an asymmetric cross-section and wherein said keying module includes means for mounting said pin in any one of a plurality descrete positions.
 13. The receptacle of claim 12 wherein said means for mounting said pin comprises a boss, integral with said keying module and having a hollow core, the internal surface of which comprises a plurality of flat sides and said metal pin also has at least two flat sides which mate with two corresponding flat sides of said core. 